be soldered to the back to hold the picture in place and
also a metal strip to hold the frame upright. These should be
placed before the metal is lacquered.

** Finding the Horsepower of Small Motors [238]

A small motor often excites curiosity as to its true horsepower,
or fraction of a horsepower. Guesses in this direction vary
remarkably for the same motor or engine. It is comparatively easy
to determine the horsepower put out by almost any machine by the
following method which is intended for small battery motors and
small steam engines.

Before giving the description, it may be well to know what
horsepower means. Horsepower is the rate of work and a unit is
equal to 33,000 ft. lb. per minute, or 550 ft. lb. per second.
That is lifting 33,000 lb. 1 ft. in one minute or 550 lb. 1 ft. in
one second. This may be applied to the problem of finding the
horsepower of a motor by fastening a piece of twine about 25 ft.
long to the shaft of the engine or motor to be tested in such a
way that when the shaft revolves it will wind up the string
similar to a windlass. Place the motor in such a position that the
twine will hang freely without touching anything: out of a high
window will do. Fasten a weight to the other end of the line as
heavy as the motor or engine can lift and still run. It must weigh
enough to slow the power down a little, but not to stop it. Mark
the position of the weight and start the motor, at the same time
accurately measuring time in minutes and seconds it takes to lift
the weight from the lowest point to the highest. Next measure
accurately the distance in feet covered by the weight in its
ascent and obtain the correct weight in pounds of the weight.

Multiply the weight by the distance covered and divide the result
by the number of minutes or fraction of a minute obtained and
divide this last result by 33,000 and the quotient will be the
horsepower of the motor or engine.

Perhaps an illustration will make this solution much plainer.
Suppose the motor will lift a weight of 1 lb. and still revolve,
30 ft. in 10 seconds or 1/6 of a minute. Multiplying 1 by 30 we
get 30, which divided by 1/6 gives 180. This in turn divided by
33,000 equals in round numbers 1/200 part of a horsepower.
--Contributed by Harold H. Cutter.

** Illusion for Window Attraction [239]

Gold fish and canary birds, living together in what seems like one
receptacle, make an unusual show window attraction. Secure two